Field of the Invention
The invention relates to a fuel tank for a motor vehicle and to a method for producing such a fuel tank.
Description of the Background Art
According to conventional practice, such fuel tanks can be produced from a thermoplastic resin, for example by extrusion blow molding or by welding injection-molded half-shells made of thermoplastic resin. In the interior of such a fuel tank, functional components of the fuel system can be accommodated, as a result of which the space requirement outside the fuel tank is reduced and, in addition, the number of required tank openings is reduced, which is advantageous with regard to emissions from the fuel tank.
DE 102 60 953 A1, which corresponds to US 2004/0129708, and which discloses a generic fuel tank which is designed as a blow-molded hollow plastic member, into the interior of which a functional component support is inserted. Various functional components, such as a fuel pump, a level indicator or valves, can be attached to the functional component support. In addition, the functional component support has supporting legs, by means of which the carrier is supported on opposite sides on the inside of the fuel tank.
In the production of the fuel tank, the functional component support is first fitted with the functional components by forming a pre-assembly unit, which is separate from the fuel tank. The assembled functional component support is then inserted into the interior of a tubular fuel tank preform made of thermoplastic resin. Subsequently, a blow molding process takes place, in which the preform is expanded to its final outer contour in a blow molding tool using blown air and application of heat. During the blow molding process, the functional component support is also welded or glued to the inside of the fuel tank in the region of its supporting legs. Accordingly, at least the supporting legs of the functional component support are made of a plastic material which is compatible with the plastic material of the fuel tank with regard to weldability.
The precisely positioned arrangement of the functional components in the interior of the fuel tank is of great importance in order to ensure the functional reliability of the fuel tank even in extreme driving situations, such as an extreme curve position or an extreme acceleration. The functional component support must therefore be rigidly connected to the plastic container by means of the supporting legs so as to ensure a torsion-proof, tilt-proof and non-slip positioning in the fuel tank.
As mentioned above, the functional component support is manufactured in common practice from a thermoplastic resin with a comparatively low material thickness. The functional component support is thus designed to be elastically compliant (i.e., with low inherent stiffness), so that overall a relatively compliant arrangement of the functional component support is achieved, which can be disadvantageous with regard to a secure positioning of the functional components.